Heat-insulating material



A walls reamed Nov. 20, 1923.

ATES

FATE

HERBERT M. SMITH, OF GREAT BARRINGTON, MASSACHUSETTS, ASSIGNOR TO STAN- LEY INSULATING COMPANY, OF GREAT BARRINGTON, MASSACHUSETTS, A 003- PORATION OF MAINE.

HEAT-INSULATING MATERIAL.

No Drawing.

T all whom it may concern:

Beit known that I, HERBERT MILLs SMITH, a citizen of the United States, residing at Great Barrington, in-the county of Berkshire and-State of Massachusetts, have invented certain new and useful Improve- .ments in Heat-Insulating Materials, of which the following is a specification. I

This invention relates to a composition of matter which is to be employed in the vacuous' spaces of vacuum bottles and other receptacles and devices, as for instance, the bottle. described in the United States Patent to William Stanley No. 1,071,817. The sort of articles described in that atent comprise two metallic shells, an outer shell and an inner container, held in spaced relation, the space being filled with finely divided material which will absorb gas at ordinary temperatures and reduce pressures, the said space being exhausted to such a degree as to greatly reduce the-conductivity for heat between the two shells. The composition of this finely divided material-is most important because it must be as light as possible so that the weight of the complete article may be kept to a minimum; in'the second place there must enter into the composition a sufiicient quantity of material which will absorb gas, while the remainder of the in gredients should be material which will not give off. gas to the space at. ordinary temperatures and in a partial vacuum. Again, the material must be such that it may be compressed to a reasonable extent without zaking or solidifying, which latter conditions would of course destroy its usefulness as a heat-insulator without adding to its capacity as a mechanical support or shock absorber.

- I have accordingly invented a heat-insulating material which when placed in a vacuous space will absorb any free molecules of gas that may be in the space or may erupt into it from the surfaces of the metallic which will not, under. ordinary temperatures of use and under the low pressures prevailing in the vacuous space, give off'gases on its own account (that is to say it is substantially inert) which may be com- 80 pressed to a point where it will afford mechanical support to the device as a whole,

eliminating the necesslty for other spacing or connecting devices between the two shells except at one end; which will have excellent Application filed September 30, 1918. Serial No. 256,286.

shock-absorbing qualities; which, particularly n its properly compressed condition, Wlll lmprove'the heat-insulating qualities of the device because of its interruption to the path of a free as molecule seeking to travel from one wal to the other; which, when properly dried, will not cake or solidifv under reasonable compression; which is substantially opaque to radiation; which can be compressed to a very high density without chang ng 1ts thermal conductivity; and which, with all, is exceedingly cheap to manufacture and harmless to handle.

The ingredients and proportions at which I have arrived after innumerable experi- Inents with all sorts of materials are as f0llow,s: I

' Materials. Parts by volume.

Kleselguhr, or dlatomaceous earth, preferably in powdered form 7 Charcoal (preferably made from soft wood) 1 I prefer that the kieselguhr or 'diatomaceous earth, should be rolled in a tumbling larrel for approximately one-half hour with mt The rolled kieselguhr or diatomaceous earth should then be passed through a revolving retort and heated to red heat, 700 to 800- centigrade in order to fracture the walls of the diatoms, and dehydrate the mass. The charcoal, (preferably made fromsoft wood) should beground to a very fine powder. This can be accomplished in a tumbling barrel with flint pebbles or any hard stories. A standard make of ball mill is preferable. The ground charcoal should be well mixed with the dehydrated kieselguhr or diatomaceous earth by rolling in a ball mill,-

and the mixture again heated to a temperature of 300 centigrade by slowly passing it through a revolving retort as low in oxygen 'as' possible in order to prevent combustion of the charcoal. The insulation should be kept from the atmosphere and packed into the space to be exhausted as quickly as possible, preferably just as it comes from the retort.

The resulting material is light in weight, possesses. the advantages enumerated above and is cheap to manufacture, involving no pebbles to break all packed lumps.

articles which are expensive in themselves or which require expensive treatment in o der'to make them available for my purposes.

I regard it as a perhaps important charac eristic of the invention that it includes the use of diatomaceous earth. This is easily dehydrated and kept dry, and on account of the rounded or curved shape of the particles lends itself readily to the necessary amount of compression without compaction. And of course the material is light and cheap. l

1 claim:

1. A finely divided heat-insulating material comprising a mixture of a gas-absorbing iii-ar erial and an inert material, with the latter preponderating in the'proportion of about seven to one.

An insulating composition consisting of a mixture of a gas absorbing material and an inert material. with the latter preponderating.

3. A heat insulating composition consisting of a mixture of finely divided gas absorbing material and a finely divided inert material with the latter preponderating.

4. An insulating composition consistin of a mixture of a gas absorbing materia and a diatomaceous earth with the latter preponderating.

An insulating composition consisting of a mixture of a finely divided gas absorbing material and a finely divided diatonaceous earth with the latter preponderat- 1n A heat insulating composition consist ing of a mixture of dehydrated diatomaceous substance and a small proportion of dry ground charcoal. v y

In testimony whereof I afiix my signature.

HERBERT M. SMITH. 

